Implantable intra- and trans-body wireless networks for therapies

ABSTRACT

A system of two or more implantable medical devices is configured to establish a wireless link between the two or more implantable medical devices and a device external to a body of a patient while the two or more implantable medical devices are implanted in the body of the patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application Ser. No. 62/585,346, titled IMPLANTABLEINTRA- AND TRANS-BODY WIRELESS NETWORKS FOR THERAPIES, filed Nov. 13,2017, the contents of which are incorporated herein in their entiretyfor all purposes.

GOVERNMENT LICENSE RIGHTS

This invention was made with government support under contract number isN66001-15-C-4019 awarded by the Defense Advanced Research ProjectsAgency (DARPA). The government has certain rights in the invention.

SUMMARY

In accordance with one aspect, there is provided a system of two or moreimplantable medical devices configured to establish a wirelesscommunication link between the medical devices while implanted in a bodyof a patient.

In some embodiments, the medical devices are configured to coordinatetherapy for the patient through the wireless communication link.

In some embodiments, the medical devices are configured to share dataprocessing load through the wireless communication link.

In some embodiments, at least one of the medical devices is configuredto be one of placed in a sleep mode and brought from the sleep mode intoan active mode based upon a signal from another at least one of themedical devices.

In some embodiments, the system is configured to establish at least onecommunication link between at least one of the two or more implantablemedical devices and an external device disposed outside of the body ofthe patient.

In some embodiments, the system is scalable and includes at least anadditional implantable medical device having at least one communicationlink with the external device. The at least one communication link mayinclude a wireless power supply link, a high-speed data link, and alow-speed data link. The two or more implantable medical devices maycommunicate with the external device utilizing a time-divisionmultiplexing protocol. Each of the two or more implantable medicaldevices may have different addresses that provide for the externaldevice to communicate separately with each of the two or moreimplantable medical devices.

In some embodiments, the system is a closed-loop system in which the twoor more implantable medical devices are configured to communicate todetermine therapy to be applied to the patient in the absence ofcommunication with an external device.

In some embodiments, each of the two or more implantable medical deviceshave a volume of less than about 2 cm³.

In some embodiments, each of the two or more implantable medical devicesincludes up to 32 different communication channels configured to one ofreceive sensor data signals or transmit stimulation signals. Thecommunication channels may be reconfigurable while the implantablemedical devices are implanted in the patient by transmission of a downlink control signal to the implantable medical devices.

In some embodiments, the two or more implantable medical devices includecommunications security algorithms including user authenticationrequirements.

In some embodiments, the two or more implantable medical devices areoperable to read signals from nerve tissue of the patient and processthe signals to provide outputs to control a prosthetic device of thepatient.

In some embodiments, the two or more implantable medical devices areconfigured to operate with mixed monopolar and bipolar stimulationmodes.

In accordance with another aspect, there is provided a system of two ormore implantable medical devices configured to establish a wireless linkbetween the two or more implantable medical devices and a deviceexternal to a body of a patient while the two or more implantablemedical devices are implanted in the body of the patient.

In some embodiments, the two or more implantable medical devices arefurther configured to establish a communication link between each otherwhile implanted in the body of the patient utilizing an intra-bodywireless communication link. The two or more implantable medical devicesmay be configured to coordinate therapy for the patient through thecommunication link between each other. The two or more implantablemedical devices may be further configured to share data processing loadthrough the communication link between each other.

In some embodiments, the device external to the body of the patient isconfigured to coordinate therapy for the patient performed by the two ormore implantable medical devices.

In some embodiments, the device external to the body of the patient isconfigured to coordinate monitoring of one or more physiologicalparameters of the patient by the two or more implantable medicaldevices. Coordinating monitoring of the one or more physiologicalparameters of the patient may include aggregating data acquired by thetwo or more implantable medical devices to produce aggregated dataregarding the one or more physiological parameters of the patient. Thedevice external to the body of the patient may be further configured tocoordinate therapy for the patient performed by the two or moreimplantable medical devices based on the aggregated data. The deviceexternal to the body of the patient may be further configured to providethe aggregated data to a diagnostic system distinct from the system. Thedevice external to the body of the patient may be further configured toprovide a recommendation for treatment of the patient based on theaggregated data.

In some embodiments, the two or more implantable medical devices areconfigured to share data processing load through the wirelesscommunication link with the device external to the body of the patient.

In some embodiments, at least one of the two or more implantable medicaldevices is configured to be one of placed in one of a plurality of lowpower modes and brought from the one of the plurality of low power modesinto an active mode based upon a signal from another of the two or moreimplantable medical devices.

In some embodiments, the system is scalable and includes at least anadditional implantable medical device having at least one communicationlink with the device external to the body of the patient. The system mayautomatically adapt to activation, deactivation, addition, or removal ofan implantable medical device from the system to coordinate monitoringand therapy of the patient utilizing each active implantable medicaldevice implanted in the patient.

In some embodiments, the at least one wireless link includes a wirelesspower supply link, a high-speed data link, and a low-speed data link.The high-speed data link may be an asymmetrical data link that uplinksdata received from sensors in the body of the patient by the two or moreimplantable medical devices to the device external to the body of thepatient. The low-speed data link may be an asymmetrical data link thatdownlinks configuration settings from the device external to the body ofthe patient to the two or more implantable medical devices.

In some embodiments, the low-speed data link comprises signals generatedby modulating current passing through the power supply link. Thelow-speed data link and the high-speed data link may be provided in asingle signal. The device external to the body of the patient mayinclude a plurality of antennas and may be configured to determine whichof the two or more implantable medical devices transmitted a signal overone of the high-speed data link or the low-speed data link based on aknown location of the two or more implantable medical devices and atiming of receipt of the signal at different antennas in the pluralityof antennas.

In some embodiments, the two or more implantable medical devicescommunicate with the device external to the body of the patientutilizing a time-division multiplexing protocol.

In some embodiments, each of the two or more implantable medical deviceshave different addresses that provide for the device external to thebody of the patient to communicate separately with each of the two ormore implantable medical devices.

In some embodiments, the system is a closed-loop system in which the twoor more implantable medical devices are configured to communicate todetermine therapy to be applied to the patient in the absence ofcommunication with an external device.

In some embodiments, each of the two or more implantable medical deviceshave a volume of less than about 4 cm³.

In some embodiments, each of the two or more implantable medical devicesincludes up to 32 different channels to tissue interfaces configured toone of receive sensor data signals or transmit stimulation signals. Theoperating parameters of the channels may be reconfigurable, while thetwo or more implantable medical devices are implanted in the patient,for each of sensing and stimulation by transmission of a down linkcontrol signal to the two or more implantable medical devices.

In some embodiments, the two or more implantable medical devices includecommunications security algorithms including authenticationrequirements. The two or more implantable medical devices may includecommunications security algorithms further including encryption.

In some embodiments, the two or more implantable medical devices areoperable to read signals from nerve tissue of the patient and processthe signals to provide outputs to control an electronic device. Theelectronic device may include a prosthetic device of the patient. Theelectronic device may include a computer system distinct from thesystem. The device external to the body of the patient may be furtherconfigured to receive an input from the computer system and adjust oneor more operating parameters of one of the device external to the bodyof the patient or the two or more implantable medical devices responsiveto receiving the input from the computer system.

In some embodiments, the two or more implantable medical devices arereconfigurable, while the two or more implantable medical devices areimplanted in the patient, to operate with mixed monopolar and bipolarstimulation modes by transmission of a down link control signal to thetwo or more implantable medical devices.

In some embodiments, the two or more implantable medical devices arereconfigurable, while the two or more implantable medical devices areimplanted in the patient, to switch between performing differentialsignal recording and performing single-ended signal recording bytransmission of a down link control signal to the two or moreimplantable medical devices.

In some embodiments, the two or more implantable medical devices arefurther configured to establish a communication link between each otherwhile implanted in the body of the patient utilizing a wiredcommunication link.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. Forpurposes of clarity, not every component may be labeled in the drawings.

In the drawings:

FIG. 1 illustrates a system including implanted therapy/diagnosticdevices linked by a communications network with the body of a patient;

FIG. 2A illustrates an embodiment of a system includingtherapy/diagnostic/control devices implanted in a human patient andassociated external sensors/controllers;

FIG. 2B illustrates another embodiment of a system includingtherapy/diagnostic/control devices implanted in a human patient andassociated external sensors/controllers;

FIG. 2C illustrates a methodology for communications between theimplants and the external controller of FIG. 2A or FIG. 2B;

FIG. 2D is a block circuit diagram of an example of an externalcontroller of the system of FIG. 2A or FIG. 2B;

FIG. 3A is an exploded view of an example of a wireless implant;

FIG. 3B illustrates external electrical connections on an externalsurface of the wireless implant of FIG. 3A for electrodes or sensors;

FIG. 4A illustrates an amplifier chip that maybe included in thewireless implant of FIG. 3A;

FIG. 4B illustrates a stimulator digital-to-analog converter chip thatmaybe included in the wireless implant of FIG. 3A;

FIG. 4C illustrates a switch matrix chip that maybe included in thewireless implant of FIG. 3A;

FIG. 4D illustrates a radio chip that maybe included in the wirelessimplant of FIG. 3A;

FIG. 4E illustrates a power supply chip that maybe included in thewireless implant of FIG. 3A;

FIG. 4F is a block diagram of circuitry of an example of a wirelessimplant;

FIG. 4G is a block diagram of a power supply circuit of an example of awireless implant;

FIG. 5 illustrates another example of a wireless implant;

FIG. 6 illustrates wireless links associated with examples of wirelessimplants;

FIG. 7A illustrates an external power coil disposed about an arm of asubject having a prosthetic hand in which four wireless implants areimplanted in the arm to read nerve signals and control the prosthetichand;

FIG. 7B is a chart of power transfer efficiency between an externalpower coil and wireless implants;

FIG. 7C is a chart of packet error rate in data transmissions to andfrom a wireless implant;

FIG. 8A illustrates wireless implants disposed in the back of a subject;

FIG. 8B illustrates wireless implants disposed in the head of a subject;

FIG. 9 illustrates the effect of compression algorithms on datameasurements acquired by an embodiment of a wireless implant;

FIG. 10 illustrates an electrode system that may be utilized withexamples of wireless implants;

FIG. 11A illustrates in act in the electrode system of FIG. 10 beingattached to a nerve;

FIG. 11B illustrates another act in the electrode system of FIG. 10being attached to a nerve;

FIG. 11C illustrates the electrode system of FIG. 10 attached to a nerveand having signal wires connected to bond pads of the electrode system;and

FIG. 12 illustrates a graph showing power consumption associated withdifferent security and safety features of systems including wirelessimplants.

DETAILED DESCRIPTION

Emerging applications in neuromodulation are increasingly involvingresponsive closed-loop stimulation that is coordinated acrossdistributed targets in the body. A driving factor in the design of newmedical implants is the growing awareness that disease often involvescomplex interactions between multiple systems in the body. Thisnetworked perspective has led to the emergence of the fields ofnetworked physiology and networked medicine. However, most chronicimplants today resemble pacemakers of the past—large, open-loop, andlimited to stimulation or recording at single locations. Key technicalchallenges overcome by aspects and embodiments disclosed herein includehigh-fidelity stimulation and recording, miniaturized hermeticpackaging, wireless connectivity for power and data, and wirelesssecurity.

Current state-of-art complex implantable devices for therapy operateindividually or based on input from an external (non-implanted) device.No system or method exists to allow implanted therapy devices tocoordinate activity or share information.

Aspects and embodiments disclosed herein include systems of one or morewirelessly connected implants capable of providing electricalstimulation and/or recording of electrical signals in muscles or nervoustissue in the body. Aspects end embodiments of the wireless implantsdisclosed herein may be far smaller than previously known implants, forexample, having a volume of about 4 cm³, 2 cm³, 1 cm³, or less.

Systems and methods for modulating a physiological process are provided.The systems and methods may provide a more effective technique forneurostimulation or neuromodulation therapies than previously knownsystems. The systems and methods may be used for neurostimulation orneuromodulation in spinal cord, vagus nerve, deep-brain, and retinalapplications. The systems and methods may also be used for sensing andmodulating activity of other biological organs and systems, including,but not limited to, cardiac muscle, skeletal muscle, bone, and bloodvessels. Signals of interest include electrical, magnetic, optical,chemical, and mechanical. The systems and methods may provide improvedtherapy or treatment than previously known systems by coordinatingtreatment or therapy across multiple implanted devices.

In some embodiments, each implant is wirelessly powered and equippedwith advanced microelectronics (ASICs) that provide 32 channels ofrecording and stimulation. In other embodiments, each implant may beprovided with greater than 32 channels of recording and stimulation.Recorded biosignals can be monitored by distributed implants, processedindividually or as aggregates, and used to trigger coordinatedstimulation therapies on-the-fly to target disease in ways notpreviously possible. Each implant can interface with multiple types oftissue interfaces, including electrodes and optical waveguides, and thenumber of networked implants can be varied based upon the patient'sclinical needs. Some embodiments of systems disclosed herein supportnetworking among as many as four wireless implants for a total of 128electrodes. Each wireless implant may be fully reconfigurable fordifferential and single-ended recording as well as mono- and multi-polarstimulation with arbitrary waveforms. Embodiments of wireless implantsdisclosed herein may operate with mixed monopolar and bipolarstimulation modes. Custom ASICs, dense printed circuit board (PCB)design, and miniaturized hermetic packaging enable a compact implantablevolume of about 2 cm³, 1 cm³, or less.

The small size of the implants disclosed herein provides for them toeasily go where other implants can not—for example, the head or smalleranatomy. Existing deep brain stimulation (DBS) systems arelarge—typically 20 cc—and require implantation in the chest with anelectrode lead tunneled through the neck and head to access the brain.However, many brain disorders, like neuropsychiatric illnesses, affectmultiple distributed neural regions that can't all be accessed byexisting systems. The network capability of the implants disclosedherein may provide new opportunities to restore balance to these brainnetworks. Potential peripheral applications that can benefit fromdistributed systems include hypertension, diabetes, incontinence, pain,reanimation of paralyzed limbs, and restoration of limb function foramputees through neuroprosthetics.

Features of aspects and embodiments of the wireless medical implantsdisclosed herein exhibit small volumes and form factors that easessurgical implantation into smaller spaces than previously possible. Asingle wearable antenna module may wirelessly power, communicate, andcontrol multiple wireless implants, for example, up to four differentimplants or more. Use of a single wearable antenna to power and controlmultiple implants eases the burden of use for patients compared tomultiple external antenna modules. A system including the externalantenna module and wireless implants requires robust power and datalinks that are tolerant to antenna misalignment. Data compressionenables low-power real-time streaming of neural data. In someembodiments, each implant may include up to 32 re-configurable channels(128 re-configurable channels for a system including four networkedimplants). In some embodiments, the wireless implants may supportmultiple types of electrode types, for example, Micro-, ECoG, DBS, Cuff,and EMG electrode types. Each implant may include functionalreconfigurability. Every channel can switch between recording andstimulation on demand while the implants are implanted in a body of apatient. Recording parameters of the implants that may be adjustedinclude bandwidth, sampling rate, and single-ended or differentialrecording modes. Stimulation parameters of the implants that may beadjusted include selection from four independent current sources, andability to generate arbitrary waveforms. Embodiments of the implantsdisclosed herein may provide for stimulation artifact suppression.Inherent isolation between different implants eliminates electricalground artifacts that are common when recording during and immediatelyafter stimulation. Each implant may feature an amplifier with a ±20 mVdynamic input range that avoids saturation ringing and fast-settlecircuitry that permits high-fidelity recording within 400 μs ofstimulation.

The systems and methods of the present disclosure may be utilized aloneor in combination with a larger system that may be used forphysiological treatment or for diagnostic purposes. The systems andmethods of the present disclosure may be utilized to gather information,control an external computer interface, or treat a subject over apredetermined period of time, or may be used indefinitely to monitor ortreat a subject. It may be used to monitor a subject, or control aphysiological condition of a subject, or induce or block a certainphysiological event. One or more components of the systems and methodsof the present disclosure may be used in a wireless configuration.

Various aspects and embodiments disclosed herein relate to networkedtherapy or diagnostic implants, and potentially external devices, forexample, external sensors or controllers, which can together allow forbetter patient therapies.

The proposed architecture includes two or more implanted devices whichcan coordinate activities together. A wireless data link between thenetworked implants allows the devices to share information related todata collected or intended actions.

One example of the benefit of a network like this is the ability for thenetwork of intra- and trans-body implants to share processingresponsibility. This means that data collected on one implant could beprocessed on another or that data could be shared and simultaneouslyprocessed by both. This system could lead to more complex or moreefficient data processing.

In addition, the network could use signaling between the implants toprovide therapy across the network. In a closed-loop network forneuroprosthetics or disease-treating implants, this would mean that thenetwork of implants would communicate over a wireless link to coordinatetherapy in the relevant areas based on information collected from anyone of the networked implants. In neuroprosthetics, these devices couldbe placed either near one another in a local part of the body andcommunicate over short distances or they could be placed globally acrossthe entire body and relay information across the whole body.

Another advantage that the proposed intra- and trans-body networkedimplants offer is the ability to save power by coordinating between themwhich units are required for the relevant task. Instead of all implantsrequiring full power at all times, the networked implants could wakeeach other up and shut each other down in a closed-loop mode based onexternal stimuli. Additionally or alternatively the different implantsin a system may be activated sequentially in a time-divisionmultiplexing methodology in accordance with a timer included in thesystem. A first implant may transition from a sleep to a wake mode toperform a desired task during a first time period and then transitionsto a sleep mode and a next of the implants transitions from a sleep to awake mode during a second time period (overlapping or non-overlappingwith the first time period) to perform a desired task and then returnsto a sleep mode and a next of the implants transitions from a sleep to awake mode during a third time period, and so on.

Another way to solve this problem without the use of wirelesslynetworked implants is to use wired, or leaded, implantable systems.While this solution does allow the implants to be networked together, itmay be less safe and uncomfortable for the patient than wirelessimplementations and may involve more complex surgery to ensure the leadstraverse the body safely. The addition of wired links and associatedconnectors further increases modes of failure for the implantablesystem, which are avoided with the wireless network.

In addition, an external device could handle the communication to andfrom each of the active implants thereby providing a link between theimplants. However, in this embodiment, energy may be wasted transmittinginformation to an external entity only to have it be re-transmitted toanother implant. In addition, this embodiment may involve bulky hardwareto be worn by the user as opposed to housing the entire system in thepatient.

Creating an intra- and trans-body wireless networks for therapies allowsthe implants to carry out more complex tasks than when not networked,including distributed processing, collective triggering, andcoordination of therapies.

In some embodiments, the networked implants act together as anindividual larger unit. In further embodiments, the implanted networkedimplants are part of a system having a dual network topology, allowingcommunication between the implants and with external devices as well.

As illustrated in FIG. 1, a plurality of networked therapy or diagnosticimplants may be implanted with the body of a patient, for example, ahuman patient. Although three networked therapy or diagnostic implantsare illustrated in FIG. 1, it is to be appreciated that aspects andembodiments of therapy or diagnostic systems disclosed herein are notlimited to including three networked therapy or diagnostic implants. Thethree networked therapy or diagnostic implants may have similar ordifferent functionality. The three networked therapy or diagnosticimplants may include one or more sensors and/or one or more electrodesto deliver electrical therapy to the patient. Any one or more of thenetworked therapy or diagnostic implants may include a controller toprovide control commands to circuitry in the same or others of thenetworked therapy or diagnostic implants. Each of the networked therapyor diagnostic implants may be in communication with another through anin-body shared network, which may be a wireless network or, in someembodiments, may include one or more wired communication links. At leastone of, and in some embodiments, each of the networked therapy ordiagnostic implants may also be in communication with an externalcontroller through an implant-external network, which may be a wirelesscommunication network. One or more other external sensors may also be incommunication with the external controller, via a wired or wirelesscommunication link. One or more other external devices, for example adistinct diagnostic device or computer system may also be incommunication with the external controller, via a wired or wirelesscommunication link.

FIGS. 2A and 2B illustrate embodiments of systems including wirelesslynetworked therapy or diagnostic implants (also referred to herein asimplantable medical devices). As illustrated, one or more activenetworked therapy or diagnostic implants/controllers may be electricallycoupled to or otherwise in communication with one or more internalbodily structures of a patient, for example, to nerves in the arm, leg,or brain of the patient. One or more active networked therapy ordiagnostic implants/controllers may be in communication with any one ormore other of the active networked therapy or diagnosticimplants/controllers via, for example, an in-body shared network, whichmay be a wireless network or, in some embodiments, may include one ormore wired communication links. An external controller located outsidethe body of the patient, for example, in an article of clothing, clippedto a belt, or carried in a holster may be in communication, for example,via a wireless network with one or more of the active networked therapyor diagnostic implants/controllers via, for example, implant-externalnetwork, which may be a wireless communication network. One or moreother externals sensors, for example a blood pressure, blood oxygenlevel, temperature, or other type of sensor may also be in communicationwith the external controller, via a wired or wireless communicationlink. The external sensors/wearable devices illustrated in FIG. 2A andFIG. 2B are located on the wrist of the patient, but in otherembodiments may be located on or proximate other portions of the body ofthe patient.

Command and control of the wireless implants may be performed over awireless low-bandwidth RF radio, which could be implemented withBluetooth® Low Energy, or a similar technology. To establish ahierarchical wireless network, the external controller is implemented asthe master and the implants are implemented as slaves. Messages are sentfrom the external master to each implanted slave to set up allocatedtime slots for each implant to transmit data back to the master using asecond high-bandwidth RF radio that operates at a separate frequencythat does not interfere with the low-bandwidth link. While operating asslaves over the low-bandwidth link, implants listen to communicationfrom the external device and await messages that are addressed to them.Each implant may be separately addressed by the external controller toprovide power and/or read or send data to each implant separately or atdifferent times. To avoid interference between simultaneous messagessent from implants to the external device, a time-division multiplexing(TDM) scheme may be used, where each implant is allocated a uniqueperiod of time in which it can transmit data to the external controller.The relative ordering and length of each implant's timeslot can beadjusted based the number of implants in the network and it's data ratein order to achieve optimal system performance. FIG. 2C illustrates amethod of communication between four implanted devices (referred to inthis figure as “satellites” or “slaves”) and an external controller(referred to in this figure as “master”) utilizing TDM.

The low-bandwidth radio can be implemented as a bi-directional link (forexample, Bluetooth® Low Energy, or similar technology) that permitsmessages to be passed from master-to-slave and also slave-to-master.Alternatively, the low-bandwidth radio can be implemented as auni-directional link using modulation of the power signal transmitted toeach implant from the external controller, or as modulation of abackscatter carrier that may be used to implement the high-bandwidthlink. Data sent from the external controller to the implants may includeconfiguration messages that can establish allocated time slots fortransmission across the high-bandwidth link, configure recordingsettings (for example, electrodes to be recorded from, differentialrecording vs single-ended, bandwidth, sampling rate, amplifier channelshut-down modes), configure stimulation settings (for example,electrodes to be stimulated on, monopolar vs bipolar vs multi-polarmodes, waveform parameters), trigger pre-loaded stimulation sequences oradjust thresholds and algorithm parameters for closed-loop stimulationtriggered by internal computation within each implant, and/or requestdevice status information (for example, impedances, voltage levels,humidity, data logs).

The high-bandwidth data link can be implemented as a uni-directionallink to stream large quantities of data (for example, physiologicalrecordings) from the implants to the external controller. Thehigh-bandwidth radio can be implemented as an active radio or as apassive backscatter communication link. In the latter, the load orimpedance on the implant's backscatter antenna is modulated such thatenergy that is reflected back the external controller contains encodedinformation. Data sent from the implants to the external device mayinclude device status, data logs, and detected faults, and recorded datafrom neurons, muscle, accelerometers, temperature, pH, and othersensors.

The external controller may contain wired and wireless links to otherexternal systems to send control signals (for example, to prostheticlimbs or computers) or receive input signals (for example, fromdiagnostic devices, prosthetic limbs, or computers). In someimplementations, the external controller may be directly wired toseparate computerized systems (for example, over a USB, optical, or CANBus cable). In other implementations, the external controller maycontain a separate wireless link (for example, RF).

A block diagram of one embodiment of an external controller that mayinterface with wireless implants as disclosed herein through an arm cuffis illustrated in FIG. 2C.

The implant provides an interface to biological tissue (for example,neurons, muscle, and/or bone) via attached electrodes, optrodes, orother sensing and stimulation interfaces. The implant interfaces may beelectrical in nature and the types of electrodes that can be usedinclude micro-electrodes, macro-electrodes, cuff, intrafascicular, EMG,DBS, ECoG, paddle, and cardiac leads. A cross-point switch matrix insideeach implant allows every channel to be used for recording andstimulation, which can be re-configured on-the-fly. The cross-pointswitch matrix also allows a bi-polar amplifier to be reconfigured fordifferential and single-ended recording modalities. Stimulation can berouted to any electrode from stimulation circuitry that providesstimulation waveforms. Multiple stimulation sources may be combined onany electrode to increase the amount of stimulation (for example,increase current).

The implant also contains circuitry for receiving wireless power fromthe external system. In some cases, a re-chargeable battery may beincluded in the implant. In other cases, the implant receives continuouswireless power without an internal battery.

The implant also contains logic for processing data and implementingclosed-loop algorithms that may trigger stimulation in response to datasensed by the implant itself, or in response to aggregated data receivedfrom the larger network of implants.

The external system provides an interface between the implanted network,the user (for example, patient or clinician) and peripheral devices (forexample, prosthetics, diagnostics, computers, or cloud computing). Datafrom implants (which may be pre-processed) is aggregated by the externalsystem and algorithms are implemented to control external systems or toprovide responsive stimulation therapies that may be distributedthroughout the implants.

FIG. 3A illustrates an example of a wireless implant 300 that may beutilized in networked implant systems as disclosed herein. The implant300 is illustrated in an exploded view and a U.S. dime is included togive an indication of size. The implant 300 includes a lid 305, anantenna board including one or more antennas 310, which may include, forexample, a inductive power link antenna, a low-bandwidth data linkantenna, and a high-bandwidth data link antenna, a ferrite andconductive shield layer 315, a PCB layer 320 including a plurality ofASICs that control operation of the implant, and a feedthrough layer325. The lid 305 and feedthrough layer 320 may con formed of abiocompatible material such as a ceramic, for example, aluminum oxide orother biocompatible ceramic. The lid 305 and feedthrough layer 325 arehermetically sealed while allowing for wireless communication to andfrom the circuitry internal to the implant 300. The feedthrough layer325 may include electrical contacts 330 that provide electricalcommunication between sensors or electrodes or other stimulation devicesexternal to the implant 300 and the circuitry within the implant 300.The electrical contacts 330 of the feedthrough layer 320 may be formedof a biocompatible conductive material, for example, a metal such asgold, or a platinum-iridium alloy, or any other biocompatible conductivematerial. Electrical contact 330 on the outside of the feedthrough layer325 are illustrated in FIG. 3B. In some embodiments, the inductive powerlink antenna may be a coil disposed within or on the outside of the lid305 and sealed against the environment internal to the body by, forexample, a layer of biocompatible polymer, rather than disposed in theantenna board 310. The wireless implant 300 may be covered in abiocompatible material, for example, silicone, with access apertures forthe electrical contacts 330.

Examples of ASICs that may be included in the implant 300, for example,on the PCB layer 320 include one or more amplifiers (FIG. 4A). The oneor more amplifiers may each support 32 channels of single endedrecording or 16 channels of differential recording. A second ASIC thatmay be included in the implant 300 is a stimulator digital-to-analogconverter (FIG. 4B). The stimulator digital-to-analog converter mayinclude, for example, four channels and be capable of outputting ±10 mAat ±10V. A third ASIC that may be included in the implant 300 is across-point switch matrix (FIG. 4C). The switch matrix may supportreconfiguration of electrodes for recording or stimulation, with a 70Ωclosed circuit impedance an >1 GΩ open circuit impedance. The switchmatrix may support the combination of multiple stimulation channels toincrease stimulation output. The switch matrix may support mapping ofmultiple references to amplifier inputs for combinations of differentialand single-ended recordings. A third ASIC that may be included in theimplant 300 is a radio circuit (FIG. 4D) that may be utilized forcommunication between different implants in the body of a subject and/orwith an external monitor or controller. The radio circuit may operateat, for example, 915 MHz with a bandwidth of 20 Mbps or more and mayoperate in accordance with the BPSK/QPSK modulation schemes. A thirdASIC that may be included in the implant 300 is a power supply (FIG.4E). The power supply may receive input power from an inductive powercoil in the antenna board 310 and output power at, for example, ±10V,3.3V, and 1.8V to provide power at appropriate voltages to the othercomponents of the implant. The implant may further include additionalintegrated circuits, discreet active devices and/or passive devices (forexample, capacitors, inductors, and/or resistors) not specificallyillustrated.

A block diagram of circuitry of an example of a wireless implant isillustrated in FIG. 4F. A block diagram of a power supply circuit of anexample of a wireless implant is illustrated in FIG. 4G.

An alternate form factor for a wireless implant 400 is illustrated inFIG. 5. The wireless implant 400 may comprise a microelectronic printedcircuit board 430, a housing 420, and a plurality of feedthroughs 410.The feedthroughs 410 may be oppositely disposed. The wireless implant400 may be constructed, for example, by fusing the housing 420 with thefeedthroughs 410, such that the printed circuit board 430 isencapsulated within the housing 420. The wireless implant 400 isillustrated with a portion of the housing 420 omitted to illustrate theinternal circuit board 430. The form factor of the wireless implant 400is illustrated in FIG. 5 may have a diameter of about 14 mm with a totalimplantable volume of about 0.7 cm³.

Embodiments of the wireless implant disclosed herein may include threerobust wireless links that are tolerant to misalignment and rotation.The three wireless links include power, low-bandwidth (LBW)bi-directional data, and high-bandwidth (HBW) uni-directional datastreaming. The three wireless links are illustrated schematically inFIG. 6 with a pair of wireless implants. Power to the wireless implantsmay be provided from an external AC power source (which may transmitpower in a radio frequency band that penetrates the body with littleattenuation) to an inductive power coil that may be included in theantenna board of the wireless implants or as a separate element of thewireless implants. FIG. 7A illustrates an external power coil 705disposed about an arm of a subject having a prosthetic hand in whichfour wireless implants 710 are implanted in the arm to read nervesignals and control the prosthetic hand. The external power coil may bein electrical communication with an external controller, for example, anexternal controller as illustrated in FIG. 2A or FIG. 2B.

In some implementations it may be desirable to align the external powercoil 705 directly over and in parallel to the power link antenna and/ordata link antennas of a wireless implant. In other implementations itmay be desirable to wind the external power coil around the body (forexample, circumscribing the arm). As illustrated in FIG. 7B, powertransfer efficiency between an external power coil and wireless implantsmay decrease with distance between the external power coil and wirelessimplants. While the wireless power efficiency between any single implantand the external power coil may decrease as more implants are added tothe system, the overall wireless efficiency of the system may increase.As illustrated in FIG. 7C packet error rate in data transmissions to andfrom a wireless implant in the high bandwidth link may increase withincreasing distance between an antenna of an external controller and awireless implant and/or with a degree of offset or misalignment betweenthe data link antennas of the wireless implant and that of the externalcontroller. Robust data transmission may be improved by implementingerror detection and correction (for example, cyclic redundancy checksand automatic repeat requests).

FIGS. 8A and 8B illustrate alternate examples of placement of wirelessimplants disclosed herein, indicated at 810, in the back and in the headof a subject, respectively.

The low-bandwidth data link may operate at a bandwidth of, for example,100 kbps and may support down-links of on-the-fly stimulation profileupdates, down-links of system firmware updates, and up-links of systemstatus and safety data. The high-bandwidth data link may operate at abandwidth of, for example, 20 Mbps and may support greater than 1,000channels of local field potential (LFP)/electromyography (EMG) data (18bit, 1,000 kilo samples per second (kSps)), 55 channels of raw spikedata (18 bit, 20 kSps), and 125 channels of compressed spike data (8bit, 20 kSps).

Increased channels of neural data, particularly spike (AP) data, createschallenges for real-time embedded processing and wireless datatransmission. Embodiments of the wireless implants disclosed herein mayimplement low-power compression algorithms that may reduce data rates inhalf (16:7) with negligible effects on spike sorting fidelity. Thisreduction of wireless data bandwidth enables power savings andtransmission of 2X more channels than might otherwise be achievable.FIG. 9 illustrates the effect of the compression algorithms on datameasurements acquired by embodiments of the wireless implants disclosedherein.

Electrodes that may be electrically connected to embodiments of thewireless implants disclosed herein may be inserted into, for example,muscle tissue or nervous tissue of a subject to monitor the electricalactivity of these tissues or apply stimulation to same. One example ofan electrode that may be utilized with embodiments of the wirelessimplants disclosed herein is referred to as a longitudinalintra-fascicular electrode (LIFE) system. The LIFE electrode systemformed of platinum and silicone and include fine features which aredesigned to be implanted within the body of a peripheral nerve of asubject. The LIFE electrode system, illustrated generally at 1000 inFIG. 10, includes a cuff 1005 having six cuff electrodes 1010 for macrorecording, stimulation, and proving a secure anchoring point around anerve. The LIFE electrode system 1000 further includes aninterfascicular active area 1015 including nine intra-neural electrodes1020 for micro recording and stimulation for more precise motor controland sensory perception. A needle 1025 at the tip of the electrode system1000 allows for easy and simplified implantation within individual motorand sensory fascicles for safer and more reliable access to targetedneurons. Bond pads 1035 on a bonding surface 1030 coupled to the cuff1005 provide electrical contact to each of the cuff electrodes 1010 andintra-neural electrodes 1020 which are in turn electrically connected toelectrical contacts 330 or feedthroughs 410 of embodiments of a wirelessimplant as disclosed herein.

In use, the LIFE electrode system is threaded into the fibers of thenerves using the suture needle 1025 located at the end of the activesites, as shown in FIG. 11A. Once the electrode system is properlyplaced, the needle is removed (FIG. 11B). The electrode system is thensecured closely to the nerve fibers to form a selective neural interfaceand the wires for connection to a wireless implant are connected to thebond pads 135 (FIG. 11C).

It should be appreciated that embodiments of the wireless implantsdisclosed herein are not limited to sending or receiving electricalsignals from electrodes. In other embodiments other forms of sensors,for example, blood pressure, blood oxygen, glucose level, insulin level,or other forms of mechanical or chemical sensors may be utilized toprovide data to embodiments of the wireless implants. In alternateembodiments, outputs of embodiments of the wireless implants may beutilized to drive a chemical dispenser or drug delivery system or todrive a heating, cooling, or light emitting device or one that appliesmechanical force to one or more portions of a body of a subject.

In some embodiments, wireless implants as disclosed herein may beprovided with wireless security measures to prevent hacking. Implantablemedical devices are typically more power constrained than externalsystems and designs of such systems may include a trade-off betweenpower and security. FIG. 12 illustrates a graph showing powerconsumption associated with different security and safety features.Embodiments of wireless implants disclosed herein may include securityalgorithms requiring authentication, for example, multi-factorauthentication or proximity-based authentication. Such algorithms may bereprogrammable. Confidentiality features of embodiments of wirelessimplants disclosed herein may include resting data encryption and/or SSLarchitecture for transit data. Data integrity features of wirelessimplants disclosed herein may include error detection and automaticrepeat request (ARQ). Availability features of embodiments of wirelessimplants disclosed herein may include an integrated network andshort-range radio.

PROPHETIC EXAMPLES Prophetic Example 1: Restoration of SensorimotorFunction in an Upper Arm Amputee Through a Sensorized Robotic Arm

An example application of a wirelessly networked implantable system isto restore sensorimotor function in an upper arm amputee through asensorized robotic arm. In this example, control of the prosthetic armcould be derived from signals recorded from residual muscle and nerve inthe amputated limb. To provide control signals for movement of theprosthetic, muscle activity could be recorded from intramuscular orepimysial electromyography (EMG) electrodes. Control signals for flexionor extension around a joint could be derived from different musclegroups that are involved in similar natural movement, which are oftenlocated on opposite sides of the limb. Two implants could be used torecord activity from each group—one located near to the extensors andone located near to the flexors. Recorded EMG activity could beprocessed within each implant. The power of the EMG signals may beestimated using an envelope detection method that rectifies and low-passfilters the raw EMG data. Alternatively, control signals could bederived from motor neurons using cuff or intrafascicular electrodes.

Targeted nerves are typically more proximal than the muscles that theyinnervate and so the location of an implant that interfaces with nervewould likely be more proximal than implants that interface with muscles.Neural recording requires a wider amplifier bandwidth and highersampling rate than EMG, and which could be configured via the wirelessdown-link to an implant. Neural signals could be processed within animplant, which might include threshold detection, action potentialsorting, and calculation of spike rates. Depending upon the chosenalgorithms, the power to wirelessly transmit the neural signals to theexternal device may be less than the power to perform the processingwithin the implant. In such instances, the neural data, which has agreater sampling rate than EMG, may be compressed and transmitted to theexternal device within an allocated time slot that is proportionallylonger in duration than the time slot duration allocated to an implantthat is recording EMG. The pre-processed signals could then beaggregated by the external device and further processed to create amovement control signal that is transmitted (wirelessly or via a wiredconnection) to the prosthetic.

To restore sensory function, both muscle and nerve could be stimulatedto create sensory perceptions in response to movement and touch on thesensorized prosthetic limb. To create a perception of limb movement,signals from the prosthetic could be received by the external device,which would then convert the signals to desired stimulation patternsthat would be sent to implants that are interfacing with the nerve ormuscle that are associated with the intended perception. Naturalsensation of limb movement involves both the contraction of somemuscles, while others are extended on the opposite side of the joint. Toreplicate this sensation, stimulation might be provided at multiplelocations in the limb through multiple distributed implants. Stimulationpatterns might be transmitted from the external device to the implantsusing the low-bandwidth downlink by sending changes in the frequency oramplitude of stimulation to be provided. In this way, the amount of datarequired for stimulation can be reduced since not all of the stimulationparameters need to be transmitted for every stimulus. Implants mayreceive the stimulation information that is addressed to them andconduct further processing to create the full stimulation pattern thatis required. The timing and location of stimulation can be coordinatedacross multiple implants to produce a natural sensation.

Prophetic Example 2: Treating Neuropsychiatric Disorders ThroughClosed-Loop Neuromodulation in the Brain

Another example application of a wirelessly networked implantable systemis to treat neuropsychiatric disorders through closed-loopneuromodulation in the brain. In this example, coordinated stimulationmay be provided at multiple target locations in the brain in response toestimates of unhealthy neuropsychiatric states derived from aggregatedneural activity that is distributed throughout the brain.Neuropsychiatric illness is increasingly understood from a systemsneuroscience perspective involving dynamic changes in network activity.For example, neural activity that is predictive of neuropsychiatricstate may come from electrocorticographic (ECoG) signals recorded fromprefrontal cortex and cingulate cortex as well as multi-unit signalsfrom micro-electrode placed deeper within the striatum. In this example,three implants may be used—one in each area. The implants used for ECoGrecordings would have their amplifiers configured for lower bandwidthdifferential recordings, and the implant used for multi-unit recordingswould be configured for higher bandwidth single-ended recordings. Powerspectra from ECoG recordings may be calculated within specific frequencybands within the implants and results wirelessly transmitted to theexternal device. Algorithms for spike thresholding, sorting, andcalculation of spike rates may be implemented in the implant configuredfor multi-unit recordings and transmitted to the external device. Thisdata may be aggregated and processed to detect the neuropsychiatricstate, which may be subsequently used to trigger coordinated stimulationon multiple electrodes distributed across all implants. Alternatively,features of the recorded signals may be transmitted directly between theimplanted network in the absence of the external device and used tomodulate stimulation therapies.

Having thus described several aspects of at least one embodiment, it isto be appreciated that various alterations, modifications, andimprovements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure and are intended to be within the scope of theinvention. Accordingly, the foregoing description and drawings are byway of example only, and the scope of the invention should be determinedfrom proper construction of the appended claims, and their equivalents.

What is claimed is:
 1. A system of two or more implantable medicaldevices configured to establish a wireless link between the two or moreimplantable medical devices and a device external to a body of a patientwhile the two or more implantable medical devices are implanted in thebody of the patient.
 2. The system of claim 1, wherein the two or moreimplantable medical devices are further configured to establish acommunication link between each other while implanted in the body of thepatient utilizing an intra-body wireless communication link.
 3. Thesystem of claim 2, wherein the two or more implantable medical devicesare configured to coordinate therapy for the patient through thecommunication link between each other.
 4. The system of claim 2, whereinthe two or more implantable medical devices are further configured toshare data processing load through the communication link between eachother.
 5. The system of claim 1, wherein the device external to the bodyof the patient is configured to coordinate therapy for the patientperformed by the two or more implantable medical devices.
 6. The systemof claim 1, wherein the device external to the body of the patient isconfigured to coordinate monitoring of one or more physiologicalparameters of the patient by the two or more implantable medicaldevices.
 7. The system of claim 6, wherein coordinating monitoring ofthe one or more physiological parameters of the patient includesaggregating data acquired by the two or more implantable medical devicesto produce aggregated data regarding the one or more physiologicalparameters of the patient.
 8. The system of claim 7, wherein the deviceexternal to the body of the patient is further configured to coordinatetherapy for the patient performed by the two or more implantable medicaldevices based on the aggregated data.
 9. The system of claim 7, whereinthe device external to the body of the patient is further configured toprovide the aggregated data to a diagnostic system distinct from thesystem.
 10. The system of claim 7, wherein the device external to thebody of the patient is further configured to provide a recommendationfor treatment of the patient based on the aggregated data.
 11. Thesystem of claim 1, wherein the two or more implantable medical devicesare configured to share data processing load through the wirelesscommunication link with the device external to the body of the patient.12. The system of claim 1, wherein at least one of the two or moreimplantable medical devices is configured to be one of placed in one ofa plurality of low power modes and brought from the one of the pluralityof low power modes into an active mode based upon a signal from anotherof the two or more implantable medical devices.
 13. The system of claim1, wherein the system is scalable and includes at least an additionalimplantable medical device having at least one communication link withthe device external to the body of the patient.
 14. The system of claim13, where the system automatically adapts to activation, deactivation,addition, or removal of an implantable medical device from the system tocoordinate monitoring and therapy of the patient utilizing each activeimplantable medical device implanted in the patient.
 15. The system ofclaim 1, wherein the at least one wireless link includes a wirelesspower supply link, a high-speed data link, and a low-speed data link.16. The system of claim 15, wherein the high-speed data link is anasymmetrical data link that uplinks data received from sensors in thebody of the patient by the two or more implantable medical devices tothe device external to the body of the patient.
 17. The system of claim15, wherein the low-speed data link is an asymmetrical data link thatdownlinks configuration settings from the device external to the body ofthe patient to the two or more implantable medical devices.
 18. Thesystem of claim 15, wherein the low-speed data link comprises signalsgenerated by modulating current passing through the power supply link.19. The system of claim 15, wherein the low-speed data link andhigh-speed data link are provided in a single signal.
 20. The system ofclaim 15, wherein the device external to the body of the patientincludes a plurality of antennas and is configured to determine which ofthe two or more implantable medical devices transmitted a signal overone of the high-speed data link or the low-speed data link based on aknown location of the two or more implantable medical devices and atiming of receipt of the signal at different antennas in the pluralityof antennas.
 21. The system of claim 1, wherein the two or moreimplantable medical devices communicate with the device external to thebody of the patient utilizing a time-division multiplexing protocol. 22.The system of claim 1, wherein each of the two or more implantablemedical devices have different addresses that provide for the deviceexternal to the body of the patient to communicate separately with eachof the two or more implantable medical devices.
 23. The system of claim1, wherein the system is a closed-loop system in which the two or moreimplantable medical devices are configured to communicate to determinetherapy to be applied to the patient in the absence of communicationwith an external device.
 24. The system of claim 1, wherein each of thetwo or more implantable medical devices have a volume of less than about4 cm³.
 25. The system of claim 1, wherein each of the two or moreimplantable medical devices includes up to 32 different channels totissue interfaces configured to one of receive sensor data signals ortransmit stimulation signals.
 26. The system of claim 25, wherein theoperating parameters of the channels are reconfigurable, while the twoor more implantable medical devices are implanted in the patient, foreach of sensing and stimulation by transmission of a down link controlsignal to the two or more implantable medical devices.
 27. The system ofclaim 1, wherein the two or more implantable medical devices includecommunications security algorithms including authenticationrequirements.
 28. The system of claim 27, wherein the two or moreimplantable medical devices include communications security algorithmsfurther including encryption.
 29. The system of claim 1, wherein the twoor more implantable medical devices are operable to read signals fromnerve tissue of the patient and process the signals to provide outputsto control an electronic device.
 30. The system of claim 29, wherein theelectronic device includes a prosthetic device of the patient.
 31. Thesystem of claim 29, wherein the electronic device includes a computersystem distinct from the system.
 32. The system of claim 31, wherein thedevice external to the body of the patient is further configured toreceive an input from the computer system and adjust one or moreoperating parameters of one of the device external to the body of thepatient or the two or more implantable medical devices responsive toreceiving the input from the computer system.
 33. The system of claim 1,wherein the two or more implantable medical devices are reconfigurable,while the two or more implantable medical devices are implanted in thepatient, to operate with mixed monopolar and bipolar stimulation modesby transmission of a down link control signal to the two or moreimplantable medical devices.
 34. The system of claim 1, wherein the twoor more implantable medical devices are reconfigurable, while the two ormore implantable medical devices are implanted in the patient, to switchbetween performing differential signal recording and performingsingle-ended signal recording by transmission of a down link controlsignal to the two or more implantable medical devices.
 35. The system ofclaim 1, wherein the two or more implantable medical devices are furtherconfigured to establish a communication link between each other whileimplanted in the body of the patient utilizing a wired communicationlink.